1. Field of the Invention
This invention relates to recoil reducing buffering (or attenuating) devices for firearm (employing an explosive charge) guns of various types, sizes, and degrees of automation; and more specifically, it relates to those types of counter-recoil apparatus employing a pneumatic-cylinder as its primary kinetic-energy absorption mechanism for both reducing mechanical-shock to the gun-structure, and to improve aiming-accuracy by reduction of xe2x80x9caim throw-offxe2x80x9d imposed by each firing kick-back; xe2x80x94also, the disclosure sets forth features to provide improved projectile powering means applicable to air-guns.
2. Relevant Prior-Art
Background research discovery provides some prior patent-art regarded as germane to this disclosure, chronologically for example U.S. Pat. No. 836,502 (Filed: April 1906) shows a portion of an early automated firearm breech employing a built-in air-chamber fitted with an annular plunger-piston acting against a recoil-spring while engaged forwardly by a rearwardly recoiling-rod member of the breech mechanism.
In U.S. Pat. No. 900,865 (Filed: March 1907) is shown an automatic magazine-fed handgun having a built-in air-chamber fitted with a plunger-piston, whereby the tubular air-chamber reacts aftward around the plunger-piston.
In U.S. Pat. No. 1,297,240 (Filed: December 1916) is shown an automatic machine-gun having a built-in air-chamber fitted with a plunger-piston, whereby rearward action of the breech-bolt is rebuffed via both a recoil-spring and the momentary compression of captive air which reactively induced compression is regulatable via an adjustable screw-adjusted relief-valve device.
In U.S. Pat. No. 1,398,452 (Filed: September 1919) is shown an automatic-rifle having an aftwardly built-in air-chamber and breech-piston arrangement obviating need of a recoil-spring.
In U.S. Pat. No. 1,351,141 (Filed: April 1920) is shown a hydraulic (oil filled) recoil-buffer spool device for automated firearms, wherein a restricting orifice is staged between two longitudinally opposite chambers; and whereby a discharge of breech pressurized oil is forced past a preferably tapered longitudinal needle-valve arranged coaxially within said orifice. The arrangement in combination with a substantially conventional recoil-spring thus serving to modulate the otherwise jolt of sliding-bolt action upon firing of the gun.
In U.S. Pat. No. 3,3298,282 (Filed: February 1965 from Germany) is shown a built-in pneumatic recoil modulator device in combination with a conventional recoil-spring for automatic type firearms, wherein a fixed full-area piston is driven within an aftwardly traveling tubular breech extension chamber; the piston thus acting in concert with the helical-spring to more smoothly arrest aftward travel of the breech-bolt.
In U.S. Pat. No. 3,636,813 (Filed: June 1969 from Germany) is shown an elaborate dual-cylinder hydraulic counter-recoil device employing full-area pistons acting within a pair of tubular barrels; which apparatus is intended for modulating the inertia-forces of recoil encountered in relatively heavy artillery weaponry thus unsuitable for hand-portable guns.
In U.S. Pat. No. 3,599,530 (Filed: November 1969) is shown an elaborate said automatic-replenisher for the hydro-pneumatic recoil systems of relatively large caliber weaponry; unsuitable for hand-portable guns.
In U.S. Pat. No. 3,901,125 (Filed: March 1973) is exemplified an automatic-pistol of the popular Colt/45-caliber sidearm type, wherein is provided a combination conventional recoil-spring and a fixed delayed-action pneumatic-chamber driven over-upon by an aftward moving cupped front breech-plug (92), whereupon piston 102 (having an O-ring seal) ensues to build-up a compressive resistance to the recoiling breech inertia. The inventor teaches that the greater breach-loading sustained by the higher recoil-resistance, enables the sent projectile to travel further down the barrel before the bolt opens, allegedly improving aiming accuracy and repeated firing comfort owing to reduced xe2x80x9ckickxe2x80x9d. The pneumatic members are at ambient-pressure (not pre-pressurized) prior to firing, and a resilient rubber-cushion (132) is required to absorb final travel; xe2x80x94some contemplation is given to a retrofitable pneumatic device adaptable to such an older gun (col.-3/lines. 4-15).
In U.S. Pat. No 4,307,653 (Filed: September 1979) and U.S. Pat. No. 4,445,644 (Filed: May 1981) are shown generic variants of a recoil buffer with interacting first and second gas-chambers (note: xe2x80x94neither of which is pre-pressurized, and some iterations include an oil medium), wherein upon recoil after firing, a compressive force is applied to the first chamber, whereby a gas/pressure-differential is generated between first and second longitudinal chambers, thus producing a gas flow into the second chamber via a venting fluid-diode restrictor device; hence, the apparatus is a type of shock-absorber only, still requiring a conventional metal recoil-spring for cyclic-action.
In U.S. Pat. No. 4,388,855 (Filed: October 1980) is shown a built-in pneumatic decelerator device for a firearm, wherein a breech air-chamber (8, not pre-pressurized) also contains a metal recoil-spring (60) and is moved aftwardly upon firing of the gun, causing fixed hollow piston member (12) to effectively slide into the air-chamber, thus compressing both the spring and the air captive therein.
In U.S. Pat. No. 4,492,050 (Filed: April 1983 from U.K.) is shown an air-powered gun having a gas-tight pressure-chamber for launching a projectile, which chamber is pressurized via a manually-actuated cocking-pump, and has no relevance to combating recoil action.
In U.S. Pat. Nos. 4,850,329 and 5,193,517 (Filed: January 1988 and June 1991) from U.K. by the Theoben-group; Is shown a firing-mechanism for air-powered guns, wherein a longitudinal cylinder (4) with an internally sliding primary-piston (5) having an extended-skirt portion also contains a free-sliding bobbin-piston (1) acting as an inertial-mass within the extended-skirt; said bobbin-piston having an axial air-port and an optional coil-spring urging bobbin-piston toward the gun""s discharge-port, the effect of which is to reduce accuracy disturbing kinetic-energy at the end of the primary-piston""s projectile launching travel.
In U.S. Pat. No. 5,076,139 (Filed: August 1990) is shown an exemplified conventional semi-automatic Beretta(mfg.) side-arm gun said to have a problematical hammering condition of the slide against the frame at maximum slide-travel, which creates destructing structural cracks in the frame. A resilient shim-like buffer device is thus retrofitable, which is said to significantly relieve the peak-loads imposed upon the frame; however, the simple device only treats the symptom, and does not eliminate the inherent mechanical defect inherent in this metal recoil-spring design.
In U.S. Pat. No. 5,265,852 (Filed: October 1991) is shown a gas-spring of the type employed widely in the tooling-Industry to reduce shock-forces encountered during mating of metal-dies; and noteworthy here is the use of a rod-like piston member, which owing to it""s reduced piston-area relative to the cylinder-bore cross-section, is able to travel within the cylinder without creating excessive increase in Internal working-pressure (as compared to a full-area piston operating within a closed cylinder).
In U.S. Pat. No. 5,339,789 (Filed: July 1992 from Germany) is shown a low-recoil air-rifle, whereto the gun-mechanism referenced by the gun-barrel/breech (20) is mounted atop a wooden-stock portion (26), whereto a special mounting is provided between the gun-barrel and the gun-stock, which employs a roller and inclined-ramp mechanism serving to alter the vector of recoil-forces sufficiently as to greatly reduce loss of target in the sights upon firing of the air-rifle. However, such an extensive alteration to conventional existing guns is not a prectical consideration.
In U.S. Pat. No. 5,513,730 (Filed: September 1995) is shown a so-called non-linear longitudinal recoil/shock-absorber apparatus for mounting abaxially to a gun-barrel for example, so as to react in a manner said to reduce recoil kick upon firing of the gun. A specially configured helical-spring is located inside the cylinderical body of the shock-absorber, which becomes axially torqued as to cause the spring to diametrically expand and impinge frictionally against the internal-wall of the cylinder chamber containing oil. However, it is believed that after extended use, the level of shock-absorption deteriorates owing to internal wear.
In U.S. Pat. No. 5,727,286 (Filed: March 1996 from Taiwan) is shown a pneumatic door-closer of the elongate cylinder type, having an adjustable/needle-valve at the otherwise occluded end of the cylinder, and a piston-shaft extending oppositely from the cylinder. However, the internal piston-head is of the full-area type, and the primary feature of the invention is a two-stage linear-action loading, whereby internal-steps upon both the cylinder-wall and the piston-shaft facilitates a convenient xe2x80x9chold-extendedxe2x80x9d function, until the user applies an overcoming retraction force, whereby the piston-shaft is biased back inward of the cylinder.
In U.S. Pat. No. 5,797,593 (Filed: December 1996from Japan) is shown an oil-dampened cylindrical so-called gas-spring apparatus common to modern automotive use as a hatch-strut, which is referenced here primarily owing to its pre-pressurized factory-sealed swedged-over non-rechargable O-ring construction.
In U.S. Pat. No. 6,059,273 (Filed: February 1995 from Sweden) is shown a cylinderical gas-spring having a full-area piston-head designed to provide relatively light initial longitudinal axial/thrust-resistance of the outwardly extending piston-shaft (4), and includes a cooperating donut-piston sliding internally on the piston-shaft, whereby greater resistance is provided once the piston-shaft has receeded slightly into the cylinder; this variable resistance action being facilitated via the internal gas-pressure/differential being impossed upon the full piston face versus the piston""s partial opposite-side surface-area.
Therefore, in full consideration of the preceding patent review, there is determined a need for an improved form of device to which these patents have been largely addressed. The instant inventor hereof believes their newly improved firearm recoil pneumatic modulator device, commercially referred to as the RECOILX-Cartridge(trademark), currently being developed for production under auspices of the Bergstrom-Mfg./Mkt.Co., exhibits certain advantages as shall be revealed in the subsequent portion of this instant disclosure.
A.) In view of the foregoing discussion about the earlier invention art, it is therefore important to make it pellucid to others interested in the art that the object of this instant invention disclosure is to provide a cylindrical preferably xe2x80x9cdrop-inxe2x80x9d pneumatic unit in place of a conventional helically-coiled steel recoil-spring heretofore typically existing within the breech-mechanism or stock-region of a conventional gun (rifled-bore firearm) or a conventional shotgun (smooth-bore firearm) of both semi-automatic and fully-automatic types thereof (as well as those heavier sorts of firearm weaponry such as semi-automatic shotguns, submachine-guns, plus military granade-launchers and cannons); xe2x80x94which serves to improve the firearm""s so called recoil-action characteristic by generally making the rate of breech opening and closing more constant as compared to that rate characteristic of metal helically-wound metal (generally carbon-steel) recoil-springs.
By replacing (OEM-substituting or aftermarket retrofitting) a conventional recoil-spring with my novel gas-spring apparatus, the former progressive-rate metal/compression-spring (becoming very increasingly resistive as the breech-mechanism travels aftward) action becomes transformed into a nearly constant-rate of recoil-action provided by my special pneumatic/compression-spring. My basic gas-spring unit also greatly abrogates the usual spring-noise resonance (virtually eliminating familiar xe2x80x9ccah""chingxe2x80x9d like vibration), while obviating off-axis (longitudinal-axis) forces, whereby reduced cycling-time (improving firing-rate), and a substantially reduced xe2x80x9ckickxe2x80x9d is realized; xe2x80x94which improved recovery-time (time required to realign a gun""s sights upon target) correlates to a consistently tighter grouping of shots at any demonstrated target distance, and significantly quieter, smoother, and more precision feeling firing-action; xe2x80x94which is thus also substantially less stressful to both gun and gunner. Accordingly, it is further asserted that these types of guns can also now be keenly redesigned as to take advantage of the significantly lower gun-frame stesses imposed by our particular gas-spring cartridge configuration, when offered as a standard OEM(original equipment manufacturer) provision.
B.) Another object of this invention disclosure is to set forth a gas-spring apparatus preferably in the form of a removable cartridge unit according to preceding item-A; wherein the cross-sectional area of the piston within the fluid-cylinder body of the cartridge is preferably substantially smaller than the cross-sectional area of the fluid-cylinder, whereby I thus refer to the piston generally as a piston-rod, owing that it preferably is less than half the cross-sectional area of the fluid-cylinder itself. Therefore, as the piston-rod makes its stroke through the fluid-cylinder, the relative differential-ratio of piston-rod cross-section diameter to cylinder cross-sectional diameter thus enables a so-called near constant compressive resistance of the piston-rod as it is plunged into the cylinderical gas-chamber of the cylinder-body. Moreover, owing to this preferred relatively diminutive effective piston-diameter, there are preferably no fluid gas-tight seals moving with the piston-rod; the fluid-seals rather being preferably fixed within the entry-bore through which the piston-rod travels. The cylinder-body is preferably of conventional circular cross-section configuration, although a non-circular shape could optionally sulfice if such were desired.
Hence, it is necessarily understood that as the manufacturing design-engineer changes the critical diameter of the piston-rod relative to the diameter of the cylinder-body, a given factory-filled static-pressure setting withstanding, xe2x80x94the characteristic increase in dynamic-pressure (a product of relative gas-chamber diameter X recoil-stroke length or travel) can now be virtually tailored to the design-engineer""s preference, from a nearly flat or xe2x80x9cnear constantxe2x80x9d compression energy profile when plotted as a graphic-chart, to a relatively steeply sloped profile compression-pressure rise more approximating that of a conventional metal/recoil-spring (albeit absent of adverse spurious mechanical aberrations characteristic of compression-springs), xe2x80x94simply by designing the piston-rod to a diameter approximating that of the cylinder within which it is operating.
In most gun applications, the ideal passive (not introducing spurious mechanical aberrations) rebuffing action enabled by invention of this disclosure, is to realize the afore stated near constant fluidic compression pressure-rise within the gas-chamber, as the piston-rod is being driven into the gas-chamber by the gun""s conventional breach action. Understandably, the diameter of the piston-rod must necessarily be designed in keeping with the degree of counter-pressure required to sustain the imposed force of the recoil-action; xe2x80x94plus, in some cases, owing to excessively confined operating-space, I am also setting forth generic-variant cartridge iterations employing compound telescopic configurations (such as a piston-rod within a piston-rod, acting either in the same direction or in opposite directions).
Generally speaking however, my cartridges are employed in a manner whereby the cylinder body portion is fixed, the usually lighter-weight piston-rod member thus acting therein against fluid-pressure, xe2x80x94moves during recoil action; xe2x80x94however if preferred, the converse arrangement can be adapted, whereby the piston-rod remains fixed and instead the cylinder-body moves yieldingly to the gun""s breech-mechanism. Alternately, it is also possible in some guns, that both the cylinder-body and the piston-rod move relative to one another; xe2x80x94either of these three implementations nevertheless achieving the object of eliminating the conventional metal/recoil-spring as shall be illustrated later herein.
Another design option is to employ seals having different coefficient-of-friction drag-loading (lighter or heavier slip-resistance) acting upon the piston-rod; a light loading generally being more suitable for guns having a positive breech locking mechanism, while a heavier type of seal-drag characteristic of generally greater contact-area is considered to be particularly appropriate for guns inherently relying upon the initial breakaway-resistance of the breech block mechanism to build-up breech-chamber pressure.
C.) Another object of this invention disclosure is to set forth the gas-spring apparatus for firearms in the form of a preferably removable drop-in cartridge unit according to preceding items-AandB, wherein the first/end-wall (or head end) portion forming the forward end of the longitudinal cylindrical body""s imperforate gas-chamber no preferably also forms a longitudinally arranged secondary/cylindrical-chamber within which is contained a free-floating inertial-mass device. This novel inertial-mass serves to effectively prolong the forward impulse during closure-sequence of a conventional breech-mechanism in a semi or-automatic or full-automatic firearm, the inertial-mass normally being held aftward within the secondary/cylindrical-chamber by a shuttle/compression-spring. In some such firearms, as the aftwardly driven bolt commences to engage and scoop the next round of ammunition slidably forward into the breech chamber, whereby the bolt necessarily becomes secured forwardly in some way (such as via a rotational cam-locking action), an irregularly-sized round or mere dirt can cause difficulty with this cyclic procedure, resulting in a so-called xe2x80x9cbounce-backxe2x80x9d event and a jam like misfire of that round (which must usually be manually cleared). Hence, I have found that the presence of an assisting secondary/inertial-mass can provide sufficient additional urging (in addition to that being provided by our gas-spring portion alone) of breech-bolt closure as to virtually overcome the impediment and efficiently drive the breech-bolt mechanism into its fully forward and securely locked position. The secondary/inertial-mass is basically a type of active-weight such as a heavy metal slug or collar, or even particulates (such as loose lead-shot), in any case necessarily normally held rearwardly in some way; xe2x80x94accordingly, as the primary-mass comes to a halt, the secondary/inertial-mass continues to thus move forward sufficiently as to effectively prolong the closing force of the breech-bolt.
D.) Another object of this invention disclosure is to set forth the gas-spring article for firearms in the form of a preferably removable drop-in cartridge unit according to preceding items-AandB, wherein I have found that some firearm implementations benefit from a novel two-in-one combination of our gas-spring operating as an assembly in longitudinal cooperation with a xe2x80x9cboosterxe2x80x9d metal/compression-spring member arranged coaxially to the gas-spring casing for those firearm applications where an increased breech closing speed is needed. Another iteration of this objective is to alternately include a xe2x80x9cmagnetic-springxe2x80x9d comprising a pair of rare-earth (preferably of neodymium type) permanent-magnets, PM-1 being arranged fixed with the gas-spring cartridge cylinder go aftward end-wall, the requisite opposing PM-2 being affixed to the inboard-terminus of the piston-rod. Thus, with their interfacing magnetic-poles arranged necessarily either plus-to-plus (+:+) or equivalently minus-to-minus (xe2x88x92:xe2x88x92), a powerful resistive energy is resultantly encountered as the piston-rod approaches its momentary aftwardly driven position.
Another related iteration of this magnetic complement to the basic gas-spring cartridge unit is in the form of a resistive-breakaway configuration, whereby the PM-1xe2x80x2 member is affixed to the inboard-terminus of the piston-rod so as to attractively interact with a PM-2xe2x80x2 an annular (encircling the concentric piston-rod) magnet affixed proximal the forward end-wall of the cartridge body. In this alternate magnetic embodiment, the function of the interacting Permanent-magnets (PM-1xe2x80x2 and PM-2xe2x80x2) is to generate a high initial-breakaway resistance, which would be particularly useful in possibly entirely obviating need for a mechanical breakaway-cam type of breech-mechanism. Thus, with their interfacing magnetic-poles arranged necessarily either plus-to-minus (+:xe2x88x92) or equivalently minus-to-plus (xe2x88x92:+), a powerful attractive magnetic-energy field is resultantly encountered as the piston-rod""s inward-terminus portion approaches its normal forwardly resting position.
E.) Another object of this invention disclosure is to set forth the gas-spring article for firearms in the form of a preferably removable drop-in cartridge unit substantially according to preceding items-AandB, yet wherein the cylindrical-wall bore portion however can be configured at the factory with variable diameters along the piston-rod""s linear path, enabling the designer still further options in the form of operating characteristics.
Accordingly, four such generic-variations are being set forth, essentially as follows: xe2x80x94all employing a piston-rod having a piston-head with an annular-seal which impinges against a reduced diameter (necked-down) portion of the cylindrical-chamber. However, in this embodiment the piston-head becomes effective only in selective portions of the gas-chamber; for example the cylindrical-wall diameter is in the generic variations of this embodiment narrowed either forwardly, aftwardly, forwardly and afterwardly, or only centrally (approximately medially), xe2x80x94thereby modifying both the pneumatic and frictional resistance and rate characteristics at which the piston-rod translates through the cylindrical-chamber.
A further generic-variant embodiment of this iteration can be realized by optionally eliminating the annular-seal from the piston-head, and establishing a critically sized by leakage-gap relative to any necked-down cylindrical-wall surfacing; thereby enabling the designer to variably regulate rate of piston-rod movement throughout the travel of the piston-rod upon firing of the gun.
F.) Another object of this invention disclosure is to set forth the gas-spring article for firearms in the form of a preferably removable drop-in cartridge unit according to preceding items-AandB, wherein the longitudinal cylindrical body of our gas-spring cartridge includes a slider-piston having an annular-seal impinging radially upon the inside-diameter of the cylindrical body while supported against the constant thrust of gas-chamber pressure via an externally adjustable preferably male/screw-threaded member acting in cooperation upon mating female/screw-threads provided upon the tubular piston-rod. Hence, the slider-piston serves to conveniently enable a degree of user adjustment of the gas-chamber positive-pressure by resultantly displacing the slider-piston forward (increasing chamber pressure) or aftward (reducing chamber pressure) relative to the gas-chamber as may be desired by the user; for example, in order to thereby tunably compensate for different types of ammunition, which explosive force directly effects the recoil reaction of the gun.
G. ) Another object of this invention relates specifically to air-powered guns instead of explosive-powered guns, wherein is provided a novel manually-selective pressure-modulator device, enabling convenient adjusting of the potential propulsive force contained within the gas-spring propulsion-chamber, which instead of an explosive-charge, serves to thrust a projectile from a conventional compressed-gas (generally air) powered gun. The overall gas-spring principle operating in similar fashion to our afore covered uniquely adjustable gas/recoil-spring for firearms, described in preceding item-C.
The pressure-modulator preferably basically comprises a longitudinally slidable attenuator-piston arranged aftwardly within the imperforate cylinderical-chamber of the air-gun""s manually actuated gas/propulsion-spring chamber (having a longitudinal-axis) and a trigger released manually recockable longitudinally reciprocating-piston having a forward thruster-head acting to launch a projectile placed within the staging-chamber of the gun""s longitudinal barrel-bore. The attenuator-piston is provided with a coaxial screw-threaded adjustor-shank extending longitudinally aftward from the air-guns""s cylindrical-chamber; whereby manual rotation of the adjustor-shank (clockwise or counter-clockwise) moves the attenuator-piston forward or aftward, as to thereby effectively vary the compression-ratio of the air contained captively within the cylindrical-chamber as desired by the gunner.
H.) GENERAL SUMMARY OF ADVANTAGES: xe2x80x94our Gas-spring serves to provide the following benefits . . . a.) to substantially reduce recoil; b.) to significantly improve time to aim; c.) to minimize vibration gain smoothness; d.) to eliminate spring noise; e.) to eliminate lateral forces; f.) to improve cycling time and durability; g.) to facilitate breech-bolt action characteristics otherwise unattainable; h.) to provide aftermarket drop-in retrofitting; i.) to enable gun-structure redesign for lighter-weight; j.) to provide quick and easy field-adjustment attuning of both firearms (breech-bolt resistance for different ammunition) and air-guns (pellet, dye-ball propulsive-thrust).